Fourier ptychography (FP) is a recently introduced technique of acquiring a high-resolution sample amplitude and phase measurement from a series of low-resolution intensity images captured under varied illumination conditions. Details of conventional FP techniques can be found in G. Zheng, R. Horstmeyer, and C. Yang, “Wide-field, high-resolution Fourier ptychographic microscopy,” Nature Photonics (2013) and in U.S. patent application Ser. No. 14/065,280 titled “Fourier Ptychographic Imaging Systems, Devices, and Methods” and filed on Oct. 28, 2013; both of which are hereby incorporated by reference in their entirety.
Conventional FP systems use an array of light emitting diodes (LEDs) or other discretized illumination source located beneath a thin, semi-transparent sample of interest as a variable illumination source. The light from each individually illuminated LED passes through the thin, semi-transparent sample and into an imaging lens (e.g., a microscope objective) to form each unique FP image which is acquired by an image sensor. The sequence of acquired images can then be combined into a high-resolution complex measurement through a phase-retrieval algorithm. These conventional FP techniques are based on the thin sample approximation and are successful for thin samples up to a thickness of 25 μm along the axial dimension, z.